In the field of biotechnology, under microscopic observation, operations of injecting sperms and sperm cells into ova and nuclei, cytoplasms, and DNAs into cells are performed. A micromanipulation system to be used in these operations is proposed, as disclosed in Japanese Patent Application Laid-Open Publication No. 2005-258413 (patent document 1). Under microscopic image observation, a micromanipulator is used in operating a micro-needle (blade tip-provided micropipette) to perform genetic recombination and microinsemination operations for test objects.
An ICSI (intracytoplasmic sperm injection method) in the microinsemination is used as an assisted reproductive technology (ART) to treat a case in which a man has a severe defect in his semen found as a result of diagnosis and observation. The microinsemination is a method of performing the entire process in vitro from the run-up of the sperm through a female genital track, the fertilization of the sperm with the ovum, and the fusion between the ovum and the sperm. The in vitro fertilization allows fertilization even in a case where the number of sperms in ejaculated semen is extremely few and a case where the sperm in the semen lacks in the ability of entering into the ovum (fertilizing ability) by itself.
In the ICSI (intracytoplasmic sperm injection method), it is necessary to directly inject the sperm into the cytoplasm inside the ovum. To this end, it is necessary for a blade tip-provided micropipette to pierce through the zona pellucid of the ovum and the egg membrane and reach into the cytoplasm. Although it is comparatively easy for a blade tip of the micropipette to pierce through the zona pellucid of the ovum, it is not easy for the blade tip to pierce through the egg membrane. This is because the egg membrane is deformed and hardened by the contact therebetween.
A vibration-type microinjection apparatus is disclosed in Japanese Patent Application Laid-Open Publication No. 2007-6775 (patent document 2). The vibration-type microinjection apparatus of the patent document 2 has the vibrator 28 having the housing which is connected in series to the micropipette 8 and on which the piezoelectric actuator 29 is mounted and the signal adjusting device 21 for adjusting electric signals applied to the piezoelectric actuator 29. By inputting the electric signals to the piezoelectric actuator 29, vibrations are axially imparted to the micropipette 8 through the vibrator 28 having the housing.